Telephony.



.S. G. BROWN. TELEPHONY. APPLICATION FILED FEB. 4, 1910.

Patented May 13, 1913.

Z? .Browzz cfdize i ticular purpose referred to,

- 35 ployed) yi ding UNITED PATENT OFFICE.

SIDNEY snonon'frnown, or Lonnou, ENGLAND.

f TELEPHONY.

To all whom it may concern Be it known that I, SIDNEY GEORGE 'Baowx,a subject of the King of Great Britain, residing at 4 Great \Vinc'hester street, in the city and county of London, England, have invented certain new and useful Improvements in or Relating-to Te-v lephony, of which the following is a specification. 7 I

This invention relates to telephony and consists ef'i n; certain improvements whereby telephonic systems are rendered more efiicient than heretofore and the intensity of the receivedsounds is increased. The improvementscan be used in connection with a microphonic transmitter, or with t a relay for the purpose of magnifying the electric or sound waves in the receiver.

Experiments have been conducted at various times with a view to determining the best conducting material or metal to use for the variable resistance contact devices employed intelephonic apparatus; carbon, osmium, iridium and'various oxidizable and non-oxidizable metals or materials possessing conducting-or other properties that would --render them efiicient as resistance ngji deViCeS have been experimented at these experiments and researches heretofore led to the. conclusion that a conducting material for the par- (owing to its comparatively high resistance and the natureof the electric current ordinarily emwa's the only material capable of satisfactory results. have found byexperiment that the efiiciency 'of a telephonic system is greatly enhanced by using in the construction of the contact device a grain or grains of osmiumiridium alloy; to obtain high efliciency the resistance of the circuF in which such a conea bon, as

" tact device is employe should bear the same relationship to the re istance of the ,metalllc contact devicev itself as the resistance of ithe telephonic circuits connected with ordinarycarbon contactdevices bear to the resistance of the latter. It is -t-herefore propo sed, according to the present invention, tojsubstitute for the ordinary carbon contact devlces heretofore employed contact devices composed of grains or fragments of osmiumiridium a loy. Osmium-iridium alloy oc-" curs in nature in the form of grams and I employ it in its natural condition for the purpose of the present invention. The

Specification of Letters Patent. i Patented 313-3 .13, 1913 Application filed February 4. 1910. Serial No. 542,023.

physical properties of i ridium render it capable of being formed; into sheets owing to its comparative softness, and although for this reaspnit is not effective as a microphone.

llga tggljlfdl lt is especially useful for forming gh'ai'd faces with which grains of the aforesaid other metals orthe alloy make contact.

The contact device formed by the use of the aforesaid metal or alloy may be arranged as a single contact or polnt, or, by the use of the metal in the-granular form, as a multiple contact. In either case the voltage on the contacts should be low; for example in the single form of the contact, the voltage may be of the value of say, one-half a volt, while in the multiple form of the contact the voltage may be of higher value-say one and one half to two volts, there being in the latter case many more points of contact over which the current is fdistributed than in the former case. If thefgr'ains are employed in the form of a column it would be possible to use a still higher voltage. The grains may however be arranged in a number or series of cells.

The lowness of the resistance-of the contact device when ofz ithe granular form will depend upon the number of contact points provided by the grains and upon the initial pressure to which the same are subjected. When the contactdevice is used in connection with a relay the sensitiveness thereof is regulated by the amount of grains employed.

A satisfactory construction of contact device consists of the-natural grains of osmiumiridium alloy, arranged in a kind of cell formed between two hard faces which are adapted to act or press upon thehard grains, the latter being retained in position by suitable means such a-s t-hose now used in the carbon contact device flof' the ordinary telephone transmitter, or *gby. an encircling band of india rubber or the iike arranged so as to inclose the space between the faces, and yet permit. of the free vibration of either or both of them.

In order that the; saidv invention may be clearly understood and readily carried into efiect, I will proceed to describe the same more fully with reference to the accompanying drawings in which I have represented several diagrammatic embodiments of the invention. r

i In the drawings :T-Figure 1 indicates a telephonic transmitter in which the contact attached to a be maintained cool by Water circulation.

participating in the movements of the diav'iding a coveringo of india rubber or other the diaphragm a.

ranged in the transmitting line with the re- 'devi'fce; is of the character hereinb'efo're described. Fig. 2 is a modified form of trans; m'itter in which the vibratory diaphragm is pivoted member, which op'er-. ates the movable contact piece'pertainin' to the contact'device. I Fig. 3 illustrates an rangement whereby the contact device may Fig. 4 shows a telephonic relay in which the metal of the contact device is in the form of grains disposed in a suitable containingcell. Fig. 5' is a similar form of relay in which the initial resistance is adjusted electrically. Fig. 6 represents a relay in which'the contact device comprises a single contact piece or point. Fig. 7 is another form of such a relay. U

Referring to Fig. 1, a is the mouth-piece of the transmitter. and a the diaphragm. which is set in vibration when the sound waves are directed through the mouthpiece so as to impinge on the said diaphragm. A contact piece at is secured to the diaphragm in such a manner as to render it capable of phragin. This contact piece is'arranged to act in conjunction with a fixed contact piece a which is mounted on a support a from which it is insulated by any suitable means, such for instance as by a bushing of vul-' canite or other insulating material.

If the member a is made of insulating material the contact piece may be directly secured thereto. The contact pieces are faced with iridium and the space between these faces is converted into a cell a by prosuitable flexible or yielding material which will be sensitive to the vibrations or movements of the movable contact piece a resulting from the action of 'the sound waves on Into the cell a a few grains of osmium iridium alloy are placed. the said grains being about one-third or one-fourth the size of the carbon granules employed in an ordinary carbon transmitter. The aforesaid cell may be approximately similar to the present carbon cell but of much smaller dimensions. A battery 6, which may be of about two volts, and the low resistance primary 6 of a transformer are arranged in series with the aforesaid contact pieces.

Z) is the secondary winding-which is arceiver 72 I In the arrangement shown in Fig. 2. the fibratory or moving contact piece a is arranged on .one extremity of a pivotally mounted lever a which adapted to preserve the faces of the contact pieces in proper operative relation so as-to permit of the requisite movement of the vibratory contact piece a relatively to the fixed or stationary contact piece at, which is carried by the casarrangement a cell a is fo'rmed between the icon'ta'ct faces, in which cell. is placed a few grains ofthe aforesaid .al-loy or metal.

'-'With a -view to avoiding heating of the contact-pieces, there 'maybe associated with,

say, the stationary contact piece, a chamber or conduit a (Fig. 3) through which is circul-ateda suitable vco0ling'm'edium, thereby maintaining the contact pieces at asuitable temperature.

' In applying the invention to a.relay,'one

arrangement is shown in Fig. 4 in which-a vibratory member such as a steel reed .c is.-

disposed inthe circuit of a battery 6' and adapted to be indirectly acted upon by the voice throughfthe line electromagnet 0 arianged adjacent thereto. cured to the framing 0 of the relay and has a conducting contact piece 0 having'a facing The reed 0 is se-' of iridium, the said contact piece being. disposed opposite to a similarly faced fixed orstationary contact-piece c "carried .by the member a, which is secured to the frame'or support of the relay. The space'betweenthe cont-act'piece's is arranged as a cell or chamber (Z, being closed or enveloped by some material (5 that is capable of yielding read- .ily when the contact pieces are subjected to relative vibration by the electric or sound.

waves. India rubber may be employed in this connection but any other material or cons trivance adapted to perform thedesired timetion may be employed. The cell (1 may com.

tain a few grains of osmium-iridium as inthe previously described arrangements. Owing to the resiliency of the reed, the dlstance between the faces of the contact pieces. is varied by the action of the aforesaid waves, and, as a result of the movements of the contact piece 0*, the grains are alternately pressed together and released from pressure; the passage of theelectric current is facilitated by the small resistance of the alloy, and variations in the strength of the current are facilitated owing to the hard and elastic character of the alloy enabling the same to instantly recover its original'form or state when the pressure to which it is subjected is released. The reed c is arranged in the circuit of a battery 0, of suitable voltage, and

the contact pieces 0 c of the relay are arranged in series with this battery and a receiver The line electromagnet 0 arranged adjacent to the reed c is energized in accordance with the electric orsound waves being transmitted in the line, and causes the reed to vibrate in accordance with such electric or sound waves.

In the arrangement shown in Fig. 5 the initial pressure between the contact pieces, and hence the normal resistance 1n the circnit of the battery 0, is controlled elect-rically in a manner. similar to that provided for adjusting the conducting space referred to in the specification of my, British Patent No. 11135 of 1908. This arrangement consists of a special winding cl provided on the electromagnet c and arranged in the battery circuit so that the, current in' saidfcircuit will energize the electromagnet and ad ust the pressure on the contact pieces. e

opposing faces of the contact pieces may be either horizontal or vertical," but the.-.'above mentioned electrical method of adjusting thepressure is especially applicable to construethe contact pieces 0, a being respectively mounted on armsor carriers e; 6 arranged on the frame 8 of the relay. The upper arm or carrier e is pivoted 0n .the a oresaid frame and carries a weight e for adjusting the initial pressure between the contact pieces, this weight being counterbalanced by an ad'ustable weight e. The contacts, which are 0 osmium-iridium. are arranged in series withthe low voltage battery 0 and the receiver e". A winding f isprovided on the magnet N and the line currents passing through the said winding are adapted to infiuence the magnet'n accordance with the sounds being transmitted.

Fig. 7 shows a form of relay similar to. that shown in Fig. 6 but in which the initial pressure between the contact pieces is not obtained by'the action of gravity but by a spring; in this case the arm e carrying the contact piece e is in the form of a blade spring and the initial pressure of the contact pieces is adjusted by means of the set screw e which bears upon the aforesaid spring arm 6. The arrangement in other respects corres onds with that already described. The e ectrical control of the initial pressure set forth in connection with Fig. 5 is equally applicable to relays of the single contact type.

In using rains of osmium-iridium alloy it is found t at owing to the hardness, elasticity and good conductivity, the vibratory contact piece is much sharper and much more definite in its action orrndvement; the

metal contact pieces closing up and opening out much more readily than carbon contacts do, thus allowing the construction of a telephone relay that can be operated efliciently y less energy than heretofore-. The hardness and elasticity of the material composing the points or surfaces of contact enables the said material to expeditlously or instantaneously resume its shape,iand the contact device to quickly resume its original resistance of contact after the deformation resulting from'the pressure incidental to the vibrations hcreinbefore referred to. It is thereforeadvantageous-tohave the faces as wella's the faces'being of such a character as to enable them, to receive the pressure inbefore :stated the best results are obtained when, the re'stance of the contact device a 4 bears the same relationship to the resistance .of .the'circuit in whichrit is included as exists between-the ,resisitance of a circuit'in which an ordinary carboncontact device is contact device. Since fin accordancewith the present invention the ontact device is me tallic'and consequen of low resistance in comparison Wlth a carbon contact device,

the resistance of thecircuit in connection with it should be correspondingly reduced.

device of such comparatively low resistance and to correspondinglyreduce the resistance of the circuit connected with it that the re; ceived sounds are so much magnified and their definitionso greatly improved.

. As the invention embodies a, device of low resistance the value of which canbe varied by variations of pressure between two parts of the device, the latter can be used in systems other than telephonic in which such an effect is desired, and can for instance be used under certain conditions in telegraphy.

ters Patent of the United States is :x 1. In electrical apparatus for magnifying electric waves or vibrations or producing the same by conversion from corresponding sound waves, a variable resistance contact device comprising fragmentary osmium an iridium alloy.

2. In electrical apparatus for magnifying electric waves or vibrations of producing the sound waves, a variable resistance contact -device comprising two hard surfaces and a granule of 'osmium-iridium'alloy interposed between the said surfaces.

3. Inelectrical apparatus'fror magnifying same 'by conversion from corresponding sound waves, a variable vresistance contact device comprising two hard surfaces and posed between the said surfaces,

4. In electrical apparatus for magnifying electric waves or vibrations or producing the same by conversion from corresponding sound waves, a variable resistance contact device comprising, and a granule of terposed between the'said surfaces. 4

and the grainsof great hardness. the grains and toreadily recover therefrom, As here-.

employed "and the resistance of the carbon It isbecau'se' it is possible touse a contact,

What I claim and desire to secure by Letsame by conversion from corresponding osmium-iridium alloy inelectric waves or vibrations or producing the granules of osmium-iridium alloy intertwo surfaces "of iridium 5. In electrical apparatus for magnifying I In testimony whereof I afiix my signature electricbwaves or vibratiierns or prcducin fithe in presence of two Witnesses. same converslon 0m corres on m 1? sound w aves, a variable resistance contacI I GEORGE 5 device comprising two surfaces of iridium I Witnesses:

and granules of osmium-iridium alloy inter- T. SELBY IVARDLEY, posed between the said surfaces. A. H. STEVENS.

Copies 01' this patent may be bbtained for in cents each, by addressing the Commissioner of iateins,

Washington, D. G. 

